<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div class="container">
      <h2 class="page_header">Promise ajax封装</h2>
      <button class="btn btn-primary" id="btn">点击发送请求</button>
    </div>
    <script>
      const btn = document.querySelector('#btn');

      btn.addEventListener('click', function () {
        const p = new Promise((res, jec) => {
          const xhr = new XMLHttpRequest();
          xhr.open('GET', 'http://poetry.apiopen.top/sentences');
          xhr.send();
          xhr.onreadystatechange = function () {
            if (xhr.readyState === 4) {
              if (xhr.status >= 200 && xhr.status < 300) {
                // console.log(xhr.response);
                res(xhr.response);
              } else {
                // console.log(xhr.status);
                jec(xhr.status);
              }
            }
          };
        }).then(
          (value) => {
            console.log(value);
          },
          (res) => {
            console.log(res);
          }
        );
      });
    </script>
  </body>
</html>
